Protected system partition read/write access on a SCSI controlled DASD

Abstract

A method and system for providing access to a protected partition of a direct access storage device in a data processing system which includes a direct access storage device, an adapter that commands I/O of the storage device and also contains a protection mechanism that restricts access to a memory partition on the storage device, an adapter device driver for controlling the adapter, and a system block device driver for transferring I/O commands to the system partition from the operating system to the adapter device driver. The method comprises the steps of receiving a request to perform a read or write to a protected memory partition, generating a command data block directing the storage device to perform the read or write, and generating a passthru command containing the command data block that directs the adapter to send the command data block without enforcing the protection of the memory partition. The method continues by sending the passthru command to the adapter which then passes the command data block on to the storage device to be executed without enforcing the memory partition protection.

What is claimed is: 
     
       1. A method in a data processing system of reading and writing to a system partition on a SCSI controlled DASD protected by a SCSI adapter address fencing mechanism, the SCSI adapter being controlled by an adapter device driver receiving I/O commands from multiple block-device-drivers, the method comprising said data processing system implemented steps of: receiving an I/O request to a memory location contained in the system partition;   generating a SCSI Command Data Block requesting an I/O of the memory location in the system partition;   generating an adapter passthru command, containing the generated SCSI Command Data Block in data field, commanding that the enclosed SCSI Command Data Block be sent to the DASD;   sending the adapter passthru command to the SCSI adapter device driver;   generating a PS/2 Micro Channel SCSI Adapter Send Other SCSI subsystem command block containing the Command Data Block as the data block;   sending the Send Other SCSI subsystem command block to the SCSI adapter; and   sending the Command Data Block over the SCSI bus to the DASD for execution of the I/O request.   
     
     
       2. A method in a data processing system of reading and writing to a system partition on a SCSI controlled DASD protected by a SCSI adapter address fencing mechanism according to claim 1, wherein the adapter device driver is an IBM2SCSI.ADD. 
     
     
       3. A method in a data processing system of reading and writing to a system partition on a SCSI controlled DASD protected by a SCSI adapter address fencing mechanism according to claim 2, wherein the adapter passthru command is an OS/2 Storage Device Driver ADAPTER --  PASSTHRU Input/output Request Block with a command modifier of EXECUTE --  CDB. 
     
     
       4. A method in a data processing system of reading and writing to a system partition on a SCSI controlled DASD protected by a SCSI adapter address fencing mechanism according to claim 1, wherein the command data block is formatted as an IEEE standard SCSI Command Data Block communication. 
     
     
       5. A method in a data processing system of reading and writing to a system partition on a SCSI controlled DASD protected by a SCSI adapter address fencing mechanism according to claim 1, further comprising the step of providing a logical drive identifier which represents the protected memory partition, and wherein the received request directs the I/O operation to the logical drive identifier. 
     
     
       6. A method in a data processing system of reading and writing to a system partition on a SCSI controlled DASD protected by a SCSI adapter address fencing mechanism according to claim 3, wherein the identifier is provided to an operating system. 
     
     
       7. A method in a data processing system of reading and writing to a system partition on a SCSI controlled DASD protected by a SCSI adapter address fencing mechanism according to claim 1, wherein the step of generating a command data block further includes addressing a particular memory location in the protected memory partition on which the I/O operation will be executed. 
     
     
       8. A method in a data processing system of reading and writing to a system partition on a SCSI controlled DASD protected by a SCSI adapter address fencing mechanism according to claim 7, wherein the memory location has a physical address equal to a logical block address offset by a relative block address of the protected memory partition. 
     
     
       9. A method in a data processing system of reading and writing to a system partition on a SCSI controlled DASD protected by a SCSI adapter address fencing mechanism according to claim 8, wherein the relative block address represents the memory device's maximum capacity minus the size of the protected memory partition. 
     
     
       10. A method in a data processing system of reading and writing to a system partition on a SCSI controlled DASD protected by a SCSI adapter address fencing mechanism according to claim 1, wherein the I/O operation is a read/write operation.